There is an idea in Robotics which I feel can cross over in most instances to the undead;"Mori's original hypothesis states that as the appearance of a robot is made more human, a human observer's emotional response to the robot will become increasingly positive and empathic, until a point is reached beyond which the response quickly becomes that of strong revulsion. However, as the robot's appearance continues to become less distinguishable from that of a human being, the emotional response becomes positive once more and approaches human-to-human empathy levels"

"The uncanny (Ger. Das Unheimliche - "the opposite of what is familiar") is a Freudian concept of an instance where something can be familiar, yet foreign at the same time, resulting in a feeling of it being uncomfortably strange or uncomfortably familiar."

I think that this is the first thing which would be felt when dealing with undead humans. The way zombies move in a not quite human, shambling way. The way that Draculas shadow had a mind of its own. Things like this would put observers in an uncomfortable state of mind and would breach the Uncanny Valley - Something which should be human acting in nearly - but not quite - human manners.

Now, the undead that manages to breach the valley and come out on the other side will be something to be feared; because something evil which can make its victims naturally feel comfortable with its presence can end up doing the most depraved things to you when your guard is down.

I think that this is the first thing which would be felt when dealing with undead humans. The way zombies move in a not quite human, shambling way. The way that Draculas shadow had a mind of its own. Things like this would put observers in an uncomfortable state of mind and would breach the Uncanny Valley - Something which should be human acting in nearly - but not quite - human manners.

I like this explanation. I wonder if there's a way to portray this during a gaming session. Seems like a great way to run an undead-heavy campaign.

Just watched it last night so it's fresh in my mind, but it seems like the animatronics in Evil Dead 2 managed to harness that kind of creepiness when the possessed humans would shift from monstrous to almost human to fully human and back again.

Now, the undead that manages to breach the valley and come out on the other side will be something to be feared; because something evil which can make its victims naturally feel comfortable with its presence can end up doing the most depraved things to you when your guard is down.

Taken out of context, that describes anti-social behavior pretty well.